Listeria Flashcards
medically most important
L monocytogenes
gram, shape, respiration, spore, catalase, where in cell, motility, hemolysis, salt, temperature
-gram positive
-rod, bacilli
-facultative anaerobe
-non spore forming
-catalase positive
-intracellular pathogen
-flagella for motility and invasion
-beta hemolytic on blood agar
-resistant to high salt
-grow at cold (4 C) temperatures
motility shape thing
umbrella shaped colony – tumbling motility
most frequently isolated form food serotype
1/2a
majority of human epidemics serotype
4b
3 most important serotypes – virulent
1/2a
1/2b
4b
culture media for growth
-mullen hinton agar with 5% sheep blood – beta hemolytic
-fastidious bacteria
-grow very slowly
issues with isolation of listeria
-requires enrichment media
-requires prolonged incubation time
improved culture for listeria isolation
-FDA BAM enrichment broth
-ISO 11290 enrichment broth
listeria is adaptive
-resistant to high salt
-survive and multiply on inanimate objects
-adapt to changing temperatures
habitat
-saprophytes in soli and decaying vegetation
-abundant in cold temperatures
host ranges
-diverse range of hosts
-more common in ruminants (mainly sheep)
-foodborne pathogen in humans
transmission
-entry – ingestion
-feeding sialge with high iron content
-exit – feces, vaginal discharge, milk
body strucutres
-flagella for motility, adhesion, invasion
-internalin (A, B, C) for adhesion, invasion
-form biofilms
-intracellular pathogen
enzymes – superoxide dismutase
-protects listeria against free radicals from host phagocytic cells
enzymes – phospholipase
-pore forming lysis in endocytosis membrane of host cell to free self from lysosome (vacuoles)
toxins – beta hemolysin
-pore forming lysis in endocytosis membrane of host cell to free self from lysosome (vacuoles)
toxins – listeriolysin O
-pore forming lysis in endocytosis membrane of host cell to free self from lysosome (vacuoles)
toxins – bacteriocins (listeriolysin S)
-kill competing gut microbiota
toxins – actin polymerizing protein (actA)
-deposition of host cell actin filaments on end of listeria
-listeria uses host cell actin filaments to propell
barriers listeria can enter
-cell membrane lipid bilayer barrier
-intestinal barrier
-placental barrier
-blood brain barrier
pathogeensis of listeria
-attachment and adhesion
-intracellular invasion
-intracellular multiplication
-spread to other cells
surfcae proteins of listeria and host epithelium
listeria – intermalin
host epithelium – E-CADHERIN
listeriosis
-febrile gastroenteritis
-septicemia, shock
-placentitis
-brainstem and cranial nerve dysfunction
neural form of listeriosis
-in silage fed to sheep
-microabscesses in brain
-ataxia and circling disease
-unilateral facial paralysis
visceral form of listeriosis
-speticemia
-gastroenteritis
-liver nad spleen damage
-fetoplacental tropism (abortion)
-myocarditis
-osteomyelitis
-mastitis
treatment
-ampicillin
-chlortetracycline
-penicillin
-trimethoprim sulfamethoxazole
control
-difficult – exist everywhere
-risk factors not well known
-vaccines – live attenuated (Norway), commercial killed (some ocuntries)
frank pathogen
-will always cause disease
-body starts fighting it as soon as it enters
intracellular pathogen?
yes
predilection site
visceral and neural infection
